Manufacture of carbon black from liquid hydrocarbons



per cubic foot.

U t tew P t e M53122? Du Bois Eastman, Whittier, Califi, assignor toTexaco Inc., a corporation of Delaware No Drawing; Application March 2,1956 Serial No. 568,963

4 Claims. (Cl. 106-407 This invention relates to a process for theproduction of carbon black, carbon monoxide, and hydrogen by reaction ofa liquid hydrocarbon with an oxygen-containing gas and to product formedthereby. In one of its more specific aspects, this invention relates toa method for producing free carbon, carbon monoxide and hydrogen bypartial oxidation of a liquid hydrocarbon with steam and free oxygen,and to the carbon so produced. This application is acontinuation-in-part of my copending application Serial No. 487,451,filed February 10, 1955, and now abandoned.

In accordance with this invention a liquid hydrocarbon is reacted withfree oxygen and steam in relativeproportions such that the hydrocarbonis converted to substantially maximum amounts of carbon monoxide andhydrogen while at the same time a substantial amount of the carboncontained in the oil is released as free carbon. The relativeproportions of the reactants are so controlled that carbon monoxide andhydrogen are the principal gaseous products. The oil is directly admixedwith and reacted with the steam and oxygen. The proportions are suchthat the reaction temperature is autogenously maintained with all of theheat, other than preheat, supplied by the reaction. In contrast, inconventional furnaceblack processes, the oil is subjected to cracking byinjection, with or without added air or oxygen,'in'to a reaction zonewherein at least a portion ofthe heat required for the process issupplied by supplemental combustion.

The process of this invention is applicable to the production of carbonfrom a normally liquid hydrocarbon. The carbon so produced has unusualproperties, as compared with carbon from conventional carbon blackprocesses, as will be evident from the following detailed description.The process is especially useful for the production of carbon black,hydrogen and carbon monoxide from heavy oil, e.g. a heavy crude or cruderesiduum. An important advantage of the present process is thesimultaneous production'of carbon monoxide and hydrogen, together with.carbon. The carbon, as well as the carbon monoxide and hydrogen, is auseful product.

The carbon produced by the process. of this invention differs from thecarbon black produced by other furnace processes. The unsettled bulkdensities of samplesof carbon p oduced by the process described hereinfall Within he range of 0.3 to 1 pound per cubic foot. Typically, the

bulk density is about 0.5 pound per cubic foot. In contrast, carbonproduced by the usual furnace black plants has a bulk density on theorder of to 12 pounds per cubic foot. Carbon from channel black plantshas a bulk density on the order of 3 pounds per cubic foot.

Samples of carbon product, as described herein, when ,mixed with Water,settle until a concentration of about 0.5 to 1 percent carbon by Weightis reached, after which no further concentration by gravity occurs. Thisrepresents a concentration of about 0.3 to 0,6 pound of carbon Incontrast, carbon from a channel a characteristic of theindividualparticlesl 2 black process when dispersed in water reaches aconcentration on settling on the order of 6 to 8 percent carbon, whilecarbon from furnace black plants reaches a concentration on the order of10 percent by weight. t

The carbon produced by the process described herein exhibitsconsiderably, higher oil absorption than carbon blacks of comparablesize and structure produced by the furnace process. Oil absorption ofrepresentative samples by the stiff paste oil absorption method is 35 to40 gallons per hundred pounds as compared with about 16 for a finefurnace black of similar structure. (Statex furnace black marketed byColumbian Carbon Company,jNew York, New York, was used as a comparisonstandard.) The stiff paste test is made by mixing linseed oil with. aone gram sample of carbon until a coherent ball is produced. Results areconverted from.cc./g. to gallons per hundred pounds. Iodine absorptionvaluesfor the same representative samples. gave values of 3 to 3%. timesthe iodine adsorption value of the comparison furnace black.

Volatile matter of the carbonblack from this process runs on the orderof 4 to 6 percent as compared with 1.4 for the comparison black. Channelblack carbon generally contains on the order of 5 percent volatilematter while furnace carbons generally contain less than about 1 /2percent volatile matter. p

Furnace blacks generally are alkaline with a pH of 7 to 9, or even ashigh as 10. The high pH of furnace black isi a disadvantage in someapplications. Channel black generally has a pH in the range of 4 to 5. Arep resentative black produced by the process of this invention (detailsof which appear below in aspecific example) hadapHof4..

Furnace processes usually produce from about 2 pounds ofreinforcingblack- (RF) tov about 4' pounds of high modulus'black (HMF)per gallon of liquid hydrocarbon. The yield of black in this process islimited to from about .1 to 1 pound per gallon. t

The ashcontent of the carbon produced by the present process may run tothe order of l to 3 percent even when distillate (minenal-free) water isused for cooling. Although the ash in furnace carbon may run as high as1.5 percent, the high ash content is generally attributed. to salts inthe water used for cooling. Ash in channel black may run as low as 0.05percent; I

Under the electron microscope, the carbon black produced by thepresentflprocess appears as small, generally spherical particles joinedtogether. in highly branched chains Ina representative sample, thespheres had an estimated mean particle diameter of the order of 40millimicrons. The individual particles of carbon, or spheres,

have very irregular. surfaces and appear pitted, and in some cases,hollow; The unusually high oil absorption and iodineadsorption valuesindicate that the surface area of the black is exceptionally-high, whichtends to confirm the observations .madeby means of the electronmicroscope as to the irregular surface characteristics of the individualparticles. v

The jetness of the carbon is considerably higher than that forfurnace-black of comparable size. Apparently this is due in part atleast. also to the pitted or hollow A sample hav-v ing a mean particlediameter of -40 milliinicrons had a higher jetness, i.e. more blacknessor:greater light absorption, than the comparison furnace black (Statex125) of comparable structure having an estimated mean particle diameterof 20 to 25. millimicrons. Generally, the smaller the particle diameterof .a carbon black, the greater the jetness. p I a The carbon producedin the present process has an unusually high afiinity'for water, i.e. itis .unusually hy- 'drophilic in characte Inacomparison test, fa sampleof black produced under conditions described hereafter other furnaceblacks.

The general structure of the carbon is similar to the lcharacteristicstructure of acetylene black produced by thermal decomposition ofacetylene by contact with heated refractory surface. Acetylene black,however, does not exhibit the high oil absorption, iodine adsorption ormoisture adsorption exhibited by the carbon produced by this process.

The product of the present process is useful in inks and paints and isparticularly useful for specialties in with great jetness is requiredand luster is not important. The product is also useful in applicationswhere a high modulus reinforcing black or a conductive black isindicated. In such cases, it is often desirable to blend the black fromthe present process with furnace black. The anomalously high absorptiveand adsorptive properties of this black indicate its application inpurification of oils and wines, in dry cell batteries, in explosives,and as trace adsorbents in electrical insulators and radio tubes.

Petroleum commonly contains small quantities of heavy metals. The mostcommon heavy metals contained in petroleum are vanadium, nickel, iron,chromium and molybdenum. These heavy metals presumably occur inpetroleum as compounds. The exact chemical compositions of the heavymetal compounds are somewhat in doubt. It is generally agreed that themetals are present, at least in part, in the form of oil-solublemetallo-organic compounds. Crude oils containing heavy metalconstituents, and some heavy distillates from such crudes, have beenfound unsatisfactory for many purposes because of the nature of the ashfrom these fuels.

The extent to which heavy metals or their compounds are present inpetroleum may vary from about 1 to about 1000 parts per million byweight. based upon the weight of the metal. In commercial operations,oils containing heavy metals are considered unsuitable as feed stock tocarbon black processes. It has been found, however, that by the processdisclosed herein, a carbon product having unique properties may beproduced and the presence of heavy metals is not detrimental to theproduct. While it is diflicult to assess the effect of heavy metals onthe properties of the product carbon, it is believed that the presenceof heavy metals in concentrationsabove 10 parts per million andpreferably above 100 parts per million are at least partiallyresponsible for the unique properties of the carbon. The foregoingtheory is advanced as a possible explanation of the fact that the carbonproduced in accordance with this invention differs from furnace blackcarbon as produced in commerce. It is to be understood, however, thatthis theory is given by way of explanation only and is not to 'beconstrued in any way as limiting the present invention. 1

Of the heavy metal constituents which normally occur in petroleum fuels,vanadium, nickel and iron occur in the greatest concentrations. Usuallypetroleum oils containing .even minor amounts of vanadium aretroublesome when used as fuel. The ash from these oils is corrosive. orerosive to both refractories and alloy metals. To a lesser extent, fueloils containing nickel and molybdenum are also troublesome from thestandpoint of corrosion and erosion Of the heavy metal contaminants,vanadium and nickel apparently are the most detrimental to refractories,particularly to aluminum oxide refractories. It has been found, however,that under conditions of partial oxidation as employed herein wherein asubstantial part of the carbon contained in the fuel, ie at least 0.5percent, is liberated as free carbon in the presence of a non-oxidizingor highly reducing atmosphere, the heavy metals have little or nodeleterious effect high temperature refractories. 7 I a E In accordancewith this invention, a hydrocarbon oil, for example a residual fuel oil,is reacted with steam and oxygen in a compact reaction zone at atemperature in the range of 2000 to 3200 F., preferably above 2250 F.and advantageously, in the range of 2500 to 2900 F. The reaction zone isfree from packing and catalyst and preferably has near-minimum internalsurface. A satisfactory reactor, as a specific example, is one in theform of a cylinder the length of which is about 2 /2 times its diameter.Reactors having a length-to-diameter ratio within the range of fromabout 1 to 4 are generally most suitable.

The reaction temperature, suitably about 2600 F., is autogenouslymaintained Preheating of the reactants is generally desirable. Theamount of uncombined oxygen supplied to the reaction zone is limited sothat near-maximum yields of carbon monoxide and hydrogen are obtained.The product consists essentially of carbon monoxide and hydrogen andcontains relatively small amounts of unconverted hydrocarbon and carbondioxide.

The reaction may be conducted at atmospheric pres- The relativeproportions of fuel, oxygen and steam required vary with various fuelsand may be readily determined by trial for any particular fuel. Thepropor' tions of oxygen, steam and hydrocarbon are balanced toautogenously maintain the desired operating temperature and extent ofcarbon conversion. It is evident that the reaction between thehydrocarbon and oxygen is highly exothermic, whereas reactions withsteam are endothermic. Steam serves the dual function of limiting themaximum temperature in the reaction zone and, at the same time, thesteam supplies oxygen for the reaction and produces hydrogen. Toconserve free oxygen, the steam preferably is preheated to a temperatureof at least 600 F. Advantageously, the steam is heated to a temperatureas high as practical, for example, to a temperature in the range of 600to 1200 F. Higher preheat temperatures are desirable but generally arenot practical. The quantity of free oxygen supplied to the reaction zoneis limited so that theconversion of carbon to carbon oxides is withinthe range of to 99.5 percent of the carbon content of the oil fed to thereaction zone. The extent of conversion of the carbon may be variedwithin this range depending upon the amounts of heavy metals containedin the fuel. The quantity ofunconverted carbon should be at least 50times and preferably at least times the combined weights of the nickeland vanadium contained in the fuels on the basis of the weight of themetal content'of the metal-containing constituents present in the fuel.The unconverted carbon from the hydrocarbon is liberated as free carbon.

The total oxygen, that is oxygen supplied by dissociation of steam,togetherwith free oxygen, generally is somewhat in excess of thetheoretical amount stoichiometrically required to convert all of thecarbon in the hydrocarbon oil .to carbon monoxide. It has been foundthat even though the total oxygen entering into the reaction is inexcess of they theoretical amount stoichiometrically required to convertall of the carbon in the fuel to carbon monoxide, free carbon is formed.This may be explainedbythe fact that some of the oxygen combines. withhydrogen from the fuel .to form water vapor.

it has been found that the gross heating value of the present invention.

oil is a convenient index of the free oxygen requirements. Fromabout 1.8to about11.9 mols offree'oxygen are required for each millionB.t.u.,sgross heating valueof the oil fed to the reactor. The freeoxygen requirements are generally within therange of from about 0.6 toabout 1.3 pounds per pound of oil while the steam requirements rangefromabout 0.2 toabout 1.5 pounds ,it, is usually undesirable to preheat.the oxygen at all, or

to preheat the oxygen to a temperature notv in excess of 600 F.Satisfactory operation may be obtained with no preheat of the oxygenfeed stream. The'hydrocarbon oil may be preheated generally to atemperature above 600 F.; the hydrocarbon preheat is limited by thecracking tendency of the particular oil. Generally, cracking limits thepractical preheat temperature to a temperature below about 800 F.Satisfactory operation is obtained by separately preheating the oil to atemperature approaching its vaporization temperature at the pressureexisting in the feed line, admixing the preheated oil with steam to forma dispersion of the oil in steam, and further preheating the dispersionto a temperature on the order of The amount of carbon dioxide in theproduct gas'is a convenient indicator in the correct relativeproportionsof fuel oil, oxygen and steam. In general, the carbon dioxide content ofthe productgas stream should be within the range of from about 2 toabout 6 percent and preferably on the order of 3 /2 to 5 /2 percent.

Ash from the fuel, particularly the heavy metal constituents, issubstantially completely retained in the carbon product. Asa result ofsequestering the ash with the. carbon, the refractory lining of thegenerator is protected from attack by the heavy metals. Theconcentration ofheavy metals in the carbon may vary from about 0.5 toabout percent by weight.

The hot gases from the generator, containing entrained carbon are cooledto a temperature below the reaction temperature, after which the carbonis separated from the gas stream. Separation may be effected byconventional means, e.g. Cottrell precipitators, cyclone separators andbag filters; In a preferred embodiment',-the hot gases from the reactionzone, containing entrained carbon, are contacted directly with water.ample, this is accomplished by discharging the gases through a submergedoutlet conduit into a body of water, and the gas stream is then furtherscrubbed for complete carbon removal by countercurent contact of the gasstream with a stream of water. The gas stream is a mixture consistingpredominantly of carbon monoxide and hydrogen, which is useful as feedgas for other commercial operations.

The following specific examples are illustrative of the In each of theexamples the generator was provided with a lining of 2 /2 inches of highpurity Alundum (aluminum oxide) sulating fire brick. a

In each of the following examples the fuel oil was a San Ardo crude oilof the following composition and physical properties.

Gravity -1 l2.8 API. Viscosity 65 0 S.F. at 122 F. Flash 235 F.Pourpoint 50 F. Conradson. carbon 9.6

Gross heating value 18,450 B.t.u./lb.

surrounded by in- In a specific exerator.

The oil was' atomizedwith steam and mixed with oxygen of 99.9 percentpurity in a flow-type gas generator of the type disclosed in US. Patent2,582,938.

Example Example 1 2 Feed Rates:

Oxygen, s.e.f./hr 5, 186 12,187 011, lbs/hr 4.01. 5 954 Steam, lbs/hr224.1 258 Mols Oz/MM B t.u of 011.. 1.847 1. 824 Operating Conditions:

Gen. Temperature (F.)- 2,600 2,850 Gen. Pressure (p.s'.i.g. a 373 .341Preheat Temperature F.)

Oil-Steam 710 740 go 67 70 Carbon Production Pounds per hour 1. 50 15.47 Unconverted carbon. (Percen 0.44 1. 89 a Dry Gas Productiom.s.e.i./hr20, 195 47,915 Product Gas Analysis-Dry Basis (Mol percent):

Hydro en 47; O 46; 51 Carbon Monoxide L 47. 0 49. 06 Carbon Dioxide 5. 53. 71 N itroeen 0. 3 0. 22 Methane 0. 1 0. Q4 Hydrogen Sulfide; 0. 1 0.44 Carbonyl Sulfide 0.02

After 186 hours of;operation under operatingconditions of high carbonconversion, representative data for which are shown in Example 1, theAiundum lining of the generator was examined and was found tobeso badlydeterioratedas to preclude further op'erationof the gen- The-lining wasreplacedand after about 673 hours of operation under conditionsofmoderate carbon conversion-,some ofthe data-for-which'are shown inExample 2, the lining was examined 'and'was found to be in excellentcondition. Operations. continued with the same generator under similarconditions of moderate carbon conversion until a total operating time ofabout .3091 hours had been accumulated. During this period a number ofheavy fuel oils were'fed to 'thesgenerator. Some of the fuel oilscontained larger amounts of vanadium and nickel, than the amountscontained in the San Ardo crude. At the end of this period, inspectionof the lining of the generator showed that it was in excellentcondition.

No evaluation was made of the carbon produced in the above examples. Thecarbon from operations of Example. 1 was not tested because operatingconditions could not be maintained over a sufficiently extended'periodof time to ensure consistent operations.

Examples 3 and 4 composition and physical properties.

Gravity 9 API.

I Viscosity 150 'S .F. at 122 F.

Flash point 285 F. Gross heating value; 18,200 B.t.u./1b. Ultimateanalysis (wt. percent):

Carbon 87 Hydrogen 10 Nitrogen 0.9 Sulfur 3 Oxygen 0.3 i

The oil is atomized with steam and mixed with oxygen of over 99 percentpurity. Operating conditions and product analyses areas' follows:

Example Example 3 4 Feed Rates:

Oxygen, 5, 258 5, 405 Oil, lbs/11 441. 9 442. 7 Steam, lbs/11L- 260. 6258. 2 Operating Oonditio Gen. Temperature. (F.) 2, 540 2, 577 Gen.Pressure (p.s.i.g.) 345 345 Preheat Temperature (F.)

' -Steam 722 71G Oxygen 62 61 Carbon Production-e- Pounds per hour 15.79 9. 69 Unconverted carbon (percent) 4. 10 2. 99 Dry Gas Production,sci/hr 22, 182 22, 500 Product Gas AnalysisDry. Basis (Mol percent):

Hydr 46. 9 46. 7 Carbon Monoxide 47. 47. 3 Carbon Dioxide 5. 2 5. 3 Nitr 0. 3 0.3 Methane 0. 4 0. 2 Hydrogen Sulfide 0.15 0.2 CarbonylSulfide 0.01 0. 02

8 Properties of the carbon produced in Examples 3 and 4 are given in thefollowing table:

iObviously, many modifications and variations of the invention ashereinbefore set forth may be made without departing from the spirit andscope thereof, and therefore only such limitations should be imposedasare indicated in the appended claims.

' I claim: g 1. As an article of manufacture, amorphous carbon black'prepared from a petroleum oil containing naturallyoccurring heavy metalcompounds, said carbon black having an unsettled bulk density within therange of 0.3 to 1' pound per cubic foot and containing from about .0.5to'about 5 weight percent heavy metals of petroleum origin comprisingvanadium.

2. A composition of matter comprising a carbon black prepared from apetroleum oil containing naturallyoccurring heavy metal compounds, saidcarbon black containing 0.5 to 10 percent by weight of heavy metals ofpetroleum origin comprising vanadium, iron, and nickel wherein vanadiumis present in largest amount.

3. As an article of manufacture, amorphous carbon black of low bulkdensity prepared from a petroleum oil containing naturally-occurringheavy metal compounds characterized by its ability'to settle in watersolely under the influence of gravity to a maximum concentration ofabout 0.5 to 1 percent carbon by weight and containing from about 0.5 toabout 5 weight percent heavy metals of petroleum origin comprisingvanadium.

4. As an article of manufacture, a hydrophilic carbon black preparedfrom a petroleum oil containing natur ally-occurring heavy metalcompounds, said carbon black containing compounds of said heavy metalsof petroleum origin. comprising vanadium and having a pH of about 4; avolatile content on the order of 5 to 6 percent; a mean particlediameter of the order of 40 millimicrons; and an irregular pittedsurface and branched chain struc ture as determined by the electronmicroscope.

References Cited in the file of this patent UNITED STATES PATENTS148,778 Tait Mar. 17, 1874 1,438,032 Frost Dec. 5, 1922 Y 1,765,991Miller June 24, 1930 1,999,573 Odell Apr. 30, 1935 2,350,846 Vogel June6, 1944 2,350,847 Vogel lune 6, 1944 2,356,471 Rehner Aug. 22, 19442,632,713 Krejci Mar. 24, 1953 2,684,896 Coghlan July 27, 1954 2,707,672Switzer May 3, 1955 2,793,938 Frank May 28, 1957 FOREIGN PATENTS 554,155Great Britain June 22, 1943

4. AS AN ARTICLE OF MANUFACTURE, A HYDROPHILIC CARBON BLACK PREPAREDFROM A PETROLEUM OIL CONTAINING NATURALLY-OCCURRING HEAVY METALCOMPOUNDS, SAID CARBON BLACK CONTAINING COMPOUNDS OF SAID HEAVY METALSOF PETROLEUM ORIGIN COMPRISING VANADIUM AND HAVING A PH OF ABOUT 4; AVOLATILE CONTENT ON THE ORDER OF 5 TO 6 PERCENT; A MEANS PARTICLEDIAMETER OF THE ORDER OF 40 MILLIMICRONS; AND AN IRREGULAR PITTEDSURFACE AND BRANCHED CHAIN STRUCTURE AS DETERMINED BY THE ELECTRONMICROSCOPE.